U.S. authorities said that a large wildfire that has consumed vast forests in one of the country's best known national parks was caused by a hunter who lost control of an illegal campfire.

The country's Forest Service said Thursday that no arrest has been made in the case and withheld the name of the hunter. Officials said there was no indication the hunter was cultivating an illegal marijuana crop, as one local fire chief had suggested.

More than 4,300 firefighters continue to battle raging flames in and near the Yosemite National Park in (the western state of) California. Officials said the wildfire that began August 17 is now 80 percent contained but that it may still be another two weeks before it is extinguished.

Officials said that more than 950 square kilometers of forests have been burned, and more than 100 structures destroyed, including 11 homes.